Mother:
The hormonal changes in your body are becoming apparent. Many are in the form of skin changes. These changes can alter how you use make up in pregnancy. You may have also developed a dark line down the middle of your abdomen to your pubic bone called a linea negra. The areola (dark nipple portion of your breasts) may have darkened and gotten larger as well. Your uterus is now the size of a grapefruit.
Baby:
The baby is now about 12.5 cms or 4.92 inches. Your baby is now producing urine and actually urinating into the amniotic fluid. It also can practice 'breathing' the amniotic fluid in and out of its lungs.
Amniotic fluid is an amazing substance. It completely regenerates itself every three hours. We do know that it is partially composed of urine from the baby, but where amniotic fluid in general is made we are not sure. Modern medicine still has some surprises left.
Twin Tips:
Amniocentesis can still be used in multiple pregnancies, be sure to talk to your practitioner if you're interested.